Process for the production of concentrated nitric acid



EERGVE PRCCESS FOR THE Pzkonucnoa OF CONCENTRATE'D MTRIG-Jygllk Filed 001.. ,14, 1921 sill Patented duly" 2 3%, 192%.

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EINAR EVE, 0L SKOIEIT, NEAR GHRISTIANIA, NORWAY, ASSIQNQR Tl) NQRSE HYDRD-ELEKTRISK KVAELSTOFAKTIESELSKAB, DE CERISTIANIA, EQRWAY.

FEQCESS FOR THE PRGDUCTIOH OF CONCENTRATED NITRIC ACID.

Application i'iled Fletcher 14, 1921. Serial life. 567,?18.

To all whom it may concern:

- Be it known that I, EINAR Bnnovn, 2 sub ject of the King of Norway, residing at Skoien, near Christisnia, Norway, heve invented certein new and useful Improvements in Processes for the Production of Concentrated Nitric Acid; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertnins to make and use the some, reference being had to the accompanying drawings, and to letters or' figures of reference marked thereon, which form a part of this specification.

This invention has for its object a process for the production of concentrated nitric acid. It'is known to produce concentrated nitric acid from liquid nitrogen oxides, oxygen and Water or dilute nitric acid by mix ing water or dilute nitric ucid with the liquid nitrogen oxides and then oxidizing the mixture with oxy en. It is necessary either to effect theoxidation under pressure or to use an excessive amount of nitrogen oxides.

In the latter case two layers of liquid are produced, the uoper consisting of e homogenous mixture 0' nitrogen oxides end nitric acid Without Water and the lower consisting of nitric acid of 80-90% which is saturated with nitrogen oxides. For the production. of

concentrated nitric acid the use of the upper, non-aqueous layer of liquid. sppecrs to he the most expedient method, the lower layer being then separated therefrom and the nitrio oxides contained in. the upper is. or he ing expelled, so that the concentrate nitric acid remains, While the lower aqueous layer is further treated with nitrogen oxides and oxygen, It is this process that has been used up till now. A

This process, however, involves the drawbeok that an larg. quantity of the nitric acid evliporates together with the nitrogen oxides.

I have now discovered. that the oxidation takes place principally in the non-aqueous layer of liquid. Experiments that have been efiected on the basis of this observation have proved that it is advantageous to let the upper, nonoqueous layer of liquid. reto the o to act upon new quantiof' i or dilute nitric acid 2 containing a. highly concentrated nitric acid of 80-90% concentration is removed and if required further treated by known methods to produce acid of a. still higher concentration. I

The cost of further concentrating this acid to a commercial product of 9 l-97% is nothing compared to the above mentioned drawback involved by the use of nonnqueous liquid.

The process can for instance he carried into efi ect in an apparatus of the following construction Dilute nitric acid and liquid nitric oxides are. supplied to stower filled With quartz. Oxygen is introduced at the bottom of the tower from where the reaction product flows into a vet and is separated into two layers. The upper, non equeous layer is pumped into the tower again Whilst the lower layer is drawn out-end subjected to further treat ment.

A constructional form of such en sp eretus is illustrated in the accompanying rewing.

of the lower layer into the tower again so that a. mixture of the liquid of both layers can circulate together, While the remeinder is drawn out for further concentration.

More than one apparatus may also be used so that part of the raw mixture of the reaction products in the first tower is conducted iuto e separate vet under another tower.

' 1 claim:

1. A process for the production of highly concentrated nitric acid, comprising the steps of reacting upon an excess qusntit of liquid nitrogen oxides with oxygen on an "queous liquid, removing the aqueous layer of the resulting reaction product, and re turning the non-aqueous layer of the said reaction product into the process.

2. A process for the production of highly concentrated nitric acid, comprising the steps of reacting upon an excess quantity of liquid nitrogen oxides with oxygen and an aqueous liquid, removing the squeous layer-oi the resulting reaction product, and returning the non-aqueous layer oi the said reaction product into the process together with pert of the hydrous layer.

3. A process for the production or highly concentrated nitric acid,com;grising reacting upon an quantity {2f liquid nitro 'en oxides with an aqussus liquid and oxygen, pr separating by gravity the resuliing product intc layers 02 an aqueaus and & mar-aqueous product am? returning the zmn-aquwusprociuat eycie m? igmmtmns.

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